Why $92,233,720,368,547,800?In binary that's 101000111101011100001010001111010111000010100011111011000. That's a 20-bit pattern that almost repeats 3 times. If we add three leading zeroes we get a nice even 60 bits and the boundaries of the pattern can be shifted without any trouble, then fix the last 7 bits to fit the pattern we get 92,233,720,368,547,758. Was this the actual sum and it got rounded before being reported by BBC? Maybe Mr. Reynolds had the extra $42 already in his account. What does this 20-bit pattern mean? 10100011110101110000Let's try IEEE floating point format. In binary scientific notation the number is 2^56 * 1.01000111101011100001010001111010111000010100011111011_2. The mantissa is one bit too long to fit in the double-precision format. If we truncate that bit our new number is 92,233,720,368,547,790 and the binary representation is 0100001101110100011110101110000101000111101011100001010001111101. The exponent doesn't follow the nice pattern we have in the mantissa and no sane person would store monetary values in a lossy format like this, so this looks like a dead-end.Back to the 20-bit pattern. We could Google search all 20 rotations of this pattern for clues, but the very first search turns up a plausible result. This pattern is the repeating bits of the binary expansion of 1/100 and would appear in the floating point representation. This suggests that somewhere in PayPal's code, one penny turned into $92 quadrillion because a floating point number was interpreted as an integer. If only my bank's software would make the same mistake.

Rich’s sh (POSIX shell) tricksThis page is meant as a repository for useful tricks I've found (and some I've perhaps invented) for scripting the POSIX shell (with some attention to portability to non-conformant shells as well, sca...

A couple articles on experimental and theoretical progress on topological insulators. These might be ...

A couple articles on experimental and theoretical progress on topological insulators. These might be among the new physical phenomena that have the greatest potential for useful applications, and are another manifestation of the beautiful interplay between topology and electromagnetism.

Some great physical explanations can be found in this 2-year-old Physics World article:

Unlike superconductors and magnets, which have order associated with a broken symmetry, topologically ordered states are distinguished by a kind of knotting of the quantum states of the electrons. This topological order “protects” the surface states, so that they cannot be eliminated by disorder or chemical passivation, and it endows them with special properties that may be useful for applications ranging from spintronics to quantum computation.http://www.physics.upenn.edu/~kane/pubs/p69.pdf

Found via this newer article recounting some of the key steps, including the recent awarding of the 2013 Physics Frontiers Prize to three pioneers of the field:

What applications these new generations of topological materials might have is probably beyond our current imagination. That being said, there is recent experimental evidence that a 1D topological superconductor can support Majorana bound states, which may be the building blocks of a fault-tolerant quantum computer. This work was in fact Science Magazine’s runner-up for the 2012 scientific breakthrough of the year, trailing only the discovery of the Higgs boson. Let’s hope this is the start of a trend!http://quantumfrontiers.com/2013/01/12/topological-insulator-trio-recognized-by-2013-physics-frontiers-prize/

Unqualified Reservations: How Bitcoin diesTL:DR - Bitcoin dies in two very simple steps. 1: A DOJ indictment is unsealed which names everyone on Planet Three who operates, or has ever operated, or perhaps who has ever even breathed on, a BTC/...

Damien Katz: The Unreasonable Effectiveness of CThe Unreasonable Effectiveness of C. For years I've tried my damnedest to get away from C. Too simple, too many details to manage, too old and crufty, too low level. I've had intense and torrid love a...